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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
27
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pubmed:dateCreated |
1993-10-20
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pubmed:abstractText |
It is believed that there are several charged amino acid residues in membrane-spanning alpha-helices of the lactose carrier of Escherichia coli. Evidence has previously been presented for two different salt bridges in membrane-spanning regions of the lactose carrier. One of these involves an interaction between Asp-237 and Lys-358; another involves interaction between Asp-240 and Lys-319. Additional studies of Lys-319 suggest that it may interact with Glu-269 as well as Asp-240. A cell containing the LacY gene with the mutation Lys-319-->Asn failed to ferment melibiose and after several days melibiose-positive mutants arose on indicator plates. These revertants showed second site mutations which replaced Asp-240 by neutral amino acids (Val or Gly). In addition, a second site mutation showed Glu-269 changed to Asn. Cells containing the mutation Lys-319-->Leu also failed to ferment melibiose and melibiose-positive revertants showed Asp-240-->Ala and Asp-240-->Tyr as well as Tyr-236-->Phe and His-322-->Arg. Second site revertants were also sought from the mutant Glu-269-->Asn which grew poorly on melibiose minimal plates. Melibiose-positive revertants included the double mutant Gln-269/Asn-319. All of the Glu-269-->Asn mutants were extremely defective in transport. It was concluded that Lys-319 interacts with Glu-269 and Asp-240 probably as salt bridges.
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pubmed:grant |
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Aspartic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/Escherichia coli Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamates,
http://linkedlifedata.com/resource/pubmed/chemical/Glutamic Acid,
http://linkedlifedata.com/resource/pubmed/chemical/LacY protein, E coli,
http://linkedlifedata.com/resource/pubmed/chemical/Lactose,
http://linkedlifedata.com/resource/pubmed/chemical/Lysine,
http://linkedlifedata.com/resource/pubmed/chemical/Melibiose,
http://linkedlifedata.com/resource/pubmed/chemical/Membrane Transport Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Monosaccharide Transport Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Oligodeoxyribonucleotides,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Symporters,
http://linkedlifedata.com/resource/pubmed/chemical/lactose permease
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pubmed:status |
MEDLINE
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pubmed:month |
Sep
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pubmed:issn |
0021-9258
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
25
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pubmed:volume |
268
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
20007-15
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:8104184-Amino Acid Sequence,
pubmed-meshheading:8104184-Aspartic Acid,
pubmed-meshheading:8104184-Base Sequence,
pubmed-meshheading:8104184-Cell Membrane,
pubmed-meshheading:8104184-Escherichia coli,
pubmed-meshheading:8104184-Escherichia coli Proteins,
pubmed-meshheading:8104184-Genes, Bacterial,
pubmed-meshheading:8104184-Genotype,
pubmed-meshheading:8104184-Glutamates,
pubmed-meshheading:8104184-Glutamic Acid,
pubmed-meshheading:8104184-Kinetics,
pubmed-meshheading:8104184-Lactose,
pubmed-meshheading:8104184-Lysine,
pubmed-meshheading:8104184-Melibiose,
pubmed-meshheading:8104184-Membrane Transport Proteins,
pubmed-meshheading:8104184-Models, Structural,
pubmed-meshheading:8104184-Molecular Sequence Data,
pubmed-meshheading:8104184-Monosaccharide Transport Proteins,
pubmed-meshheading:8104184-Mutagenesis, Site-Directed,
pubmed-meshheading:8104184-Oligodeoxyribonucleotides,
pubmed-meshheading:8104184-Protein Structure, Secondary,
pubmed-meshheading:8104184-Recombinant Proteins,
pubmed-meshheading:8104184-Symporters
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pubmed:year |
1993
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pubmed:articleTitle |
Lysine 319 interacts with both glutamic acid 269 and aspartic acid 240 in the lactose carrier of Escherichia coli.
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pubmed:affiliation |
Department of Cellular and Molecular Physiology, Harvard Medical School, Boston, Massachusetts 02115.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, U.S. Gov't, Non-P.H.S.
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